Initial import of qemu-2.4.1HEADmaster

7 files changed, 2528 insertions, 0 deletions

diff --git a/roms/ipxe/src/image/efi_image.c b/roms/ipxe/src/image/efi_image.c
new file mode 100644
index 00000000..b7d8f9c6
--- /dev/null
+++ b/roms/ipxe/src/image/efi_image.c
@@ -0,0 +1,316 @@
+/*
+ * Copyright (C) 2008 Michael Brown <mbrown@fensystems.co.uk>.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation; either version 2 of the
+ * License, or any later version.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
+ * 02110-1301, USA.
+ */
+
+FILE_LICENCE ( GPL2_OR_LATER );
+
+#include <errno.h>
+#include <stdlib.h>
+#include <wchar.h>
+#include <ipxe/efi/efi.h>
+#include <ipxe/efi/efi_snp.h>
+#include <ipxe/efi/efi_download.h>
+#include <ipxe/efi/efi_file.h>
+#include <ipxe/efi/efi_utils.h>
+#include <ipxe/efi/efi_strings.h>
+#include <ipxe/efi/efi_wrap.h>
+#include <ipxe/image.h>
+#include <ipxe/init.h>
+#include <ipxe/features.h>
+#include <ipxe/uri.h>
+
+FEATURE ( FEATURE_IMAGE, "EFI", DHCP_EB_FEATURE_EFI, 1 );
+
+/* Disambiguate the various error causes */
+#define EINFO_EEFI_LOAD							\
+	__einfo_uniqify ( EINFO_EPLATFORM, 0x01,			\
+			  "Could not load image" )
+#define EINFO_EEFI_LOAD_PROHIBITED					\
+	__einfo_platformify ( EINFO_EEFI_LOAD, EFI_SECURITY_VIOLATION,	\
+			      "Image prohibited by security policy" )
+#define EEFI_LOAD_PROHIBITED						\
+	__einfo_error ( EINFO_EEFI_LOAD_PROHIBITED )
+#define EEFI_LOAD( efirc ) EPLATFORM ( EINFO_EEFI_LOAD, efirc,		\
+				       EEFI_LOAD_PROHIBITED )
+#define EINFO_EEFI_START						\
+	__einfo_uniqify ( EINFO_EPLATFORM, 0x02,			\
+			  "Could not start image" )
+#define EEFI_START( efirc ) EPLATFORM ( EINFO_EEFI_START, efirc )
+
+/**
+ * Create device path for image
+ *
+ * @v image		EFI image
+ * @v parent		Parent device path
+ * @ret path		Device path, or NULL on failure
+ *
+ * The caller must eventually free() the device path.
+ */
+static EFI_DEVICE_PATH_PROTOCOL *
+efi_image_path ( struct image *image, EFI_DEVICE_PATH_PROTOCOL *parent ) {
+	EFI_DEVICE_PATH_PROTOCOL *path;
+	FILEPATH_DEVICE_PATH *filepath;
+	EFI_DEVICE_PATH_PROTOCOL *end;
+	size_t name_len;
+	size_t prefix_len;
+	size_t filepath_len;
+	size_t len;
+
+	/* Calculate device path lengths */
+	end = efi_devpath_end ( parent );
+	prefix_len = ( ( void * ) end - ( void * ) parent );
+	name_len = strlen ( image->name );
+	filepath_len = ( SIZE_OF_FILEPATH_DEVICE_PATH +
+			 ( name_len + 1 /* NUL */ ) * sizeof ( wchar_t ) );
+	len = ( prefix_len + filepath_len + sizeof ( *end ) );
+
+	/* Allocate device path */
+	path = zalloc ( len );
+	if ( ! path )
+		return NULL;
+
+	/* Construct device path */
+	memcpy ( path, parent, prefix_len );
+	filepath = ( ( ( void * ) path ) + prefix_len );
+	filepath->Header.Type = MEDIA_DEVICE_PATH;
+	filepath->Header.SubType = MEDIA_FILEPATH_DP;
+	filepath->Header.Length[0] = ( filepath_len & 0xff );
+	filepath->Header.Length[1] = ( filepath_len >> 8 );
+	efi_snprintf ( filepath->PathName, ( name_len + 1 /* NUL */ ),
+		       "%s", image->name );
+	end = ( ( ( void * ) filepath ) + filepath_len );
+	end->Type = END_DEVICE_PATH_TYPE;
+	end->SubType = END_ENTIRE_DEVICE_PATH_SUBTYPE;
+	end->Length[0] = sizeof ( *end );
+
+	return path;
+}
+
+/**
+ * Create command line for image
+ *
+ * @v image             EFI image
+ * @ret cmdline		Command line, or NULL on failure
+ */
+static wchar_t * efi_image_cmdline ( struct image *image ) {
+	wchar_t *cmdline;
+	size_t len;
+
+	len = ( strlen ( image->name ) +
+		( image->cmdline ?
+		  ( 1 /* " " */ + strlen ( image->cmdline ) ) : 0 ) );
+	cmdline = zalloc ( ( len + 1 /* NUL */ ) * sizeof ( wchar_t ) );
+	if ( ! cmdline )
+		return NULL;
+	efi_snprintf ( cmdline, ( len + 1 /* NUL */ ), "%s%s%s",
+		       image->name,
+		       ( image->cmdline ? " " : "" ),
+		       ( image->cmdline ? image->cmdline : "" ) );
+	return cmdline;
+}
+
+/**
+ * Execute EFI image
+ *
+ * @v image		EFI image
+ * @ret rc		Return status code
+ */
+static int efi_image_exec ( struct image *image ) {
+	EFI_BOOT_SERVICES *bs = efi_systab->BootServices;
+	struct efi_snp_device *snpdev;
+	EFI_DEVICE_PATH_PROTOCOL *path;
+	union {
+		EFI_LOADED_IMAGE_PROTOCOL *image;
+		void *interface;
+	} loaded;
+	EFI_HANDLE handle;
+	wchar_t *cmdline;
+	EFI_STATUS efirc;
+	int rc;
+
+	/* Find an appropriate device handle to use */
+	snpdev = last_opened_snpdev();
+	if ( ! snpdev ) {
+		DBGC ( image, "EFIIMAGE %p could not identify SNP device\n",
+		       image );
+		rc = -ENODEV;
+		goto err_no_snpdev;
+	}
+
+	/* Install file I/O protocols */
+	if ( ( rc = efi_file_install ( snpdev->handle ) ) != 0 ) {
+		DBGC ( image, "EFIIMAGE %p could not install file protocol: "
+		       "%s\n", image, strerror ( rc ) );
+		goto err_file_install;
+	}
+
+	/* Install iPXE download protocol */
+	if ( ( rc = efi_download_install ( snpdev->handle ) ) != 0 ) {
+		DBGC ( image, "EFIIMAGE %p could not install iPXE download "
+		       "protocol: %s\n", image, strerror ( rc ) );
+		goto err_download_install;
+	}
+
+	/* Create device path for image */
+	path = efi_image_path ( image, snpdev->path );
+	if ( ! path ) {
+		DBGC ( image, "EFIIMAGE %p could not create device path\n",
+		       image );
+		rc = -ENOMEM;
+		goto err_image_path;
+	}
+
+	/* Create command line for image */
+	cmdline = efi_image_cmdline ( image );
+	if ( ! cmdline ) {
+		DBGC ( image, "EFIIMAGE %p could not create command line\n",
+		       image );
+		rc = -ENOMEM;
+		goto err_cmdline;
+	}
+
+	/* Attempt loading image */
+	if ( ( efirc = bs->LoadImage ( FALSE, efi_image_handle, path,
+				       user_to_virt ( image->data, 0 ),
+				       image->len, &handle ) ) != 0 ) {
+		/* Not an EFI image */
+		rc = -EEFI_LOAD ( efirc );
+		DBGC ( image, "EFIIMAGE %p could not load: %s\n",
+		       image, strerror ( rc ) );
+		goto err_load_image;
+	}
+
+	/* Get the loaded image protocol for the newly loaded image */
+	efirc = bs->OpenProtocol ( handle, &efi_loaded_image_protocol_guid,
+				   &loaded.interface, efi_image_handle,
+				   NULL, EFI_OPEN_PROTOCOL_GET_PROTOCOL );
+	if ( efirc ) {
+		/* Should never happen */
+		rc = -EEFI ( efirc );
+		goto err_open_protocol;
+	}
+
+	/* Some EFI 1.10 implementations seem not to fill in DeviceHandle */
+	if ( loaded.image->DeviceHandle == NULL ) {
+		DBGC ( image, "EFIIMAGE %p filling in missing DeviceHandle\n",
+		       image );
+		loaded.image->DeviceHandle = snpdev->handle;
+	}
+
+	/* Sanity checks */
+	assert ( loaded.image->ParentHandle == efi_image_handle );
+	assert ( loaded.image->DeviceHandle == snpdev->handle );
+	assert ( loaded.image->LoadOptionsSize == 0 );
+	assert ( loaded.image->LoadOptions == NULL );
+
+	/* Set command line */
+	loaded.image->LoadOptions = cmdline;
+	loaded.image->LoadOptionsSize =
+		( ( wcslen ( cmdline ) + 1 /* NUL */ ) * sizeof ( wchar_t ) );
+
+	/* Release network devices for use via SNP */
+	efi_snp_release();
+
+	/* Wrap calls made by the loaded image (for debugging) */
+	efi_wrap ( handle );
+
+	/* Start the image */
+	if ( ( efirc = bs->StartImage ( handle, NULL, NULL ) ) != 0 ) {
+		rc = -EEFI_START ( efirc );
+		DBGC ( image, "EFIIMAGE %p could not start (or returned with "
+		       "error): %s\n", image, strerror ( rc ) );
+		goto err_start_image;
+	}
+
+	/* Success */
+	rc = 0;
+
+ err_start_image:
+	efi_snp_claim();
+ err_open_protocol:
+	/* If there was no error, then the image must have been
+	 * started and returned successfully.  It either unloaded
+	 * itself, or it intended to remain loaded (e.g. it was a
+	 * driver).  We therefore do not unload successful images.
+	 *
+	 * If there was an error, attempt to unload the image.  This
+	 * may not work.  In particular, there is no way to tell
+	 * whether an error returned from StartImage() was due to
+	 * being unable to start the image (in which case we probably
+	 * should call UnloadImage()), or due to the image itself
+	 * returning an error (in which case we probably should not
+	 * call UnloadImage()).  We therefore ignore any failures from
+	 * the UnloadImage() call itself.
+	 */
+	if ( rc != 0 )
+		bs->UnloadImage ( handle );
+ err_load_image:
+	free ( cmdline );
+ err_cmdline:
+	free ( path );
+ err_image_path:
+	efi_download_uninstall ( snpdev->handle );
+ err_download_install:
+	efi_file_uninstall ( snpdev->handle );
+ err_file_install:
+ err_no_snpdev:
+	return rc;
+}
+
+/**
+ * Probe EFI image
+ *
+ * @v image		EFI file
+ * @ret rc		Return status code
+ */
+static int efi_image_probe ( struct image *image ) {
+	EFI_BOOT_SERVICES *bs = efi_systab->BootServices;
+	static EFI_DEVICE_PATH_PROTOCOL empty_path = {
+		.Type = END_DEVICE_PATH_TYPE,
+		.SubType = END_ENTIRE_DEVICE_PATH_SUBTYPE,
+		.Length[0] = sizeof ( empty_path ),
+	};
+	EFI_HANDLE handle;
+	EFI_STATUS efirc;
+	int rc;
+
+	/* Attempt loading image */
+	if ( ( efirc = bs->LoadImage ( FALSE, efi_image_handle, &empty_path,
+				       user_to_virt ( image->data, 0 ),
+				       image->len, &handle ) ) != 0 ) {
+		/* Not an EFI image */
+		rc = -EEFI_LOAD ( efirc );
+		DBGC ( image, "EFIIMAGE %p could not load: %s\n",
+		       image, strerror ( rc ) );
+		return rc;
+	}
+
+	/* Unload the image.  We can't leave it loaded, because we
+	 * have no "unload" operation.
+	 */
+	bs->UnloadImage ( handle );
+
+	return 0;
+}
+
+/** EFI image type */
+struct image_type efi_image_type __image_type ( PROBE_NORMAL ) = {
+	.name = "EFI",
+	.probe = efi_image_probe,
+	.exec = efi_image_exec,
+};
diff --git a/roms/ipxe/src/image/elf.c b/roms/ipxe/src/image/elf.c
new file mode 100644
index 00000000..51636a8e
--- /dev/null
+++ b/roms/ipxe/src/image/elf.c
@@ -0,0 +1,185 @@
+/*
+ * Copyright (C) 2007 Michael Brown <mbrown@fensystems.co.uk>.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation; either version 2 of the
+ * License, or any later version.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
+ * 02110-1301, USA.
+ */
+
+FILE_LICENCE ( GPL2_OR_LATER );
+
+/**
+ * @file
+ *
+ * ELF image format
+ *
+ * A "pure" ELF image is not a bootable image.  There are various
+ * bootable formats based upon ELF (e.g. Multiboot), which share
+ * common ELF-related functionality.
+ */
+
+#include <errno.h>
+#include <elf.h>
+#include <ipxe/uaccess.h>
+#include <ipxe/segment.h>
+#include <ipxe/image.h>
+#include <ipxe/elf.h>
+
+typedef Elf32_Ehdr	Elf_Ehdr;
+typedef Elf32_Phdr	Elf_Phdr;
+typedef Elf32_Off	Elf_Off;
+#define ELFCLASS	ELFCLASS32
+
+/**
+ * Load ELF segment into memory
+ *
+ * @v image		ELF file
+ * @v phdr		ELF program header
+ * @v ehdr		ELF executable header
+ * @ret entry		Entry point, if found
+ * @ret max		Maximum used address
+ * @ret rc		Return status code
+ */
+static int elf_load_segment ( struct image *image, Elf_Phdr *phdr,
+			      Elf_Ehdr *ehdr, physaddr_t *entry,
+			      physaddr_t *max ) {
+	physaddr_t dest;
+	physaddr_t end;
+	userptr_t buffer;
+	unsigned long e_offset;
+	int rc;
+
+	/* Do nothing for non-PT_LOAD segments */
+	if ( phdr->p_type != PT_LOAD )
+		return 0;
+
+	/* Check segment lies within image */
+	if ( ( phdr->p_offset + phdr->p_filesz ) > image->len ) {
+		DBGC ( image, "ELF %p segment outside image\n", image );
+		return -ENOEXEC;
+	}
+
+	/* Find start address: use physical address for preference,
+	 * fall back to virtual address if no physical address
+	 * supplied.
+	 */
+	dest = phdr->p_paddr;
+	if ( ! dest )
+		dest = phdr->p_vaddr;
+	if ( ! dest ) {
+		DBGC ( image, "ELF %p segment loads to physical address 0\n",
+		       image );
+		return -ENOEXEC;
+	}
+	buffer = phys_to_user ( dest );
+	end = ( dest + phdr->p_memsz );
+
+	DBGC ( image, "ELF %p loading segment [%x,%x) to [%x,%x,%x)\n", image,
+	       phdr->p_offset, ( phdr->p_offset + phdr->p_filesz ),
+	       phdr->p_paddr, ( phdr->p_paddr + phdr->p_filesz ),
+	       ( phdr->p_paddr + phdr->p_memsz ) );
+
+	/* Verify and prepare segment */
+	if ( ( rc = prep_segment ( buffer, phdr->p_filesz,
+				   phdr->p_memsz ) ) != 0 ) {
+		DBGC ( image, "ELF %p could not prepare segment: %s\n",
+		       image, strerror ( rc ) );
+		return rc;
+	}
+
+	/* Update maximum used address, if applicable */
+	if ( end > *max )
+		*max = end;
+
+	/* Copy image to segment */
+	memcpy_user ( buffer, 0, image->data, phdr->p_offset, phdr->p_filesz );
+
+	/* Set execution address, if it lies within this segment */
+	if ( ( e_offset = ( ehdr->e_entry - dest ) ) < phdr->p_filesz ) {
+		*entry = ehdr->e_entry;
+		DBGC ( image, "ELF %p found physical entry point at %lx\n",
+		       image, *entry );
+	} else if ( ( e_offset = ( ehdr->e_entry - phdr->p_vaddr ) )
+		    < phdr->p_filesz ) {
+		if ( ! *entry ) {
+			*entry = ( dest + e_offset );
+			DBGC ( image, "ELF %p found virtual entry point at %lx"
+			       " (virt %lx)\n", image, *entry,
+			       ( ( unsigned long ) ehdr->e_entry ) );
+		}
+	}
+
+	return 0;
+}
+
+/**
+ * Load ELF image into memory
+ *
+ * @v image		ELF file
+ * @ret entry		Entry point
+ * @ret max		Maximum used address
+ * @ret rc		Return status code
+ */
+int elf_load ( struct image *image, physaddr_t *entry, physaddr_t *max ) {
+	static const uint8_t e_ident[] = {
+		[EI_MAG0]	= ELFMAG0,
+		[EI_MAG1]	= ELFMAG1,
+		[EI_MAG2]	= ELFMAG2,
+		[EI_MAG3]	= ELFMAG3,
+		[EI_CLASS]	= ELFCLASS,
+	};
+	Elf_Ehdr ehdr;
+	Elf_Phdr phdr;
+	Elf_Off phoff;
+	unsigned int phnum;
+	int rc;
+
+	/* Read ELF header */
+	copy_from_user ( &ehdr, image->data, 0, sizeof ( ehdr ) );
+	if ( memcmp ( &ehdr.e_ident[EI_MAG0], e_ident,
+		      sizeof ( e_ident ) ) != 0 ) {
+		DBGC ( image, "ELF %p has invalid signature\n", image );
+		return -ENOEXEC;
+	}
+
+	/* Initialise maximum used address */
+	*max = 0;
+
+	/* Invalidate entry point */
+	*entry = 0;
+
+	/* Read ELF program headers */
+	for ( phoff = ehdr.e_phoff , phnum = ehdr.e_phnum ; phnum ;
+	      phoff += ehdr.e_phentsize, phnum-- ) {
+		if ( phoff > image->len ) {
+			DBGC ( image, "ELF %p program header %d outside "
+			       "image\n", image, phnum );
+			return -ENOEXEC;
+		}
+		copy_from_user ( &phdr, image->data, phoff, sizeof ( phdr ) );
+		if ( ( rc = elf_load_segment ( image, &phdr, &ehdr,
+					       entry, max ) ) != 0 ) {
+			return rc;
+		}
+	}
+
+	/* Check for a valid execution address */
+	if ( ! *entry ) {
+		DBGC ( image, "ELF %p entry point %lx outside image\n",
+		       image, ( ( unsigned long ) ehdr.e_entry ) );
+		return -ENOEXEC;
+	}
+
+	return 0;
+}
diff --git a/roms/ipxe/src/image/embedded.c b/roms/ipxe/src/image/embedded.c
new file mode 100644
index 00000000..6358378f
--- /dev/null
+++ b/roms/ipxe/src/image/embedded.c
@@ -0,0 +1,91 @@
+/** @file
+ *
+ * Embedded image support
+ *
+ * Embedded images are images built into the iPXE binary and do not require
+ * fetching over the network.
+ */
+
+FILE_LICENCE ( GPL2_OR_LATER );
+
+#include <string.h>
+#include <ipxe/image.h>
+#include <ipxe/uaccess.h>
+#include <ipxe/init.h>
+
+/* Raw image data for all embedded images */
+#undef EMBED
+#define EMBED( _index, _path, _name )					\
+	extern char embedded_image_ ## _index ## _data[];		\
+	extern char embedded_image_ ## _index ## _len[];		\
+	__asm__ ( ".section \".rodata\", \"a\", @progbits\n\t"		\
+		  "\nembedded_image_" #_index "_data:\n\t"		\
+		  ".incbin \"" _path "\"\n\t"				\
+		  "\nembedded_image_" #_index "_end:\n\t"		\
+		  ".equ embedded_image_" #_index "_len, "		\
+			"( embedded_image_" #_index "_end - "		\
+			"  embedded_image_" #_index "_data )\n\t"	\
+		  ".previous\n\t" );
+EMBED_ALL
+
+/* Image structures for all embedded images */
+#undef EMBED
+#define EMBED( _index, _path, _name ) {					\
+	.refcnt = REF_INIT ( ref_no_free ),				\
+	.name = _name,							\
+	.data = ( userptr_t ) ( embedded_image_ ## _index ## _data ),	\
+	.len = ( size_t ) embedded_image_ ## _index ## _len,		\
+},
+static struct image embedded_images[] = {
+	EMBED_ALL
+};
+
+/**
+ * Register all embedded images
+ */
+static void embedded_init ( void ) {
+	int i;
+	struct image *image;
+	void *data;
+	int rc;
+
+	/* Skip if we have no embedded images */
+	if ( ! sizeof ( embedded_images ) )
+		return;
+
+	/* Fix up data pointers and register images */
+	for ( i = 0 ; i < ( int ) ( sizeof ( embedded_images ) /
+				    sizeof ( embedded_images[0] ) ) ; i++ ) {
+		image = &embedded_images[i];
+
+		/* virt_to_user() cannot be used in a static
+		 * initialiser, so we cast the pointer to a userptr_t
+		 * in the initialiser and fix it up here.  (This will
+		 * actually be a no-op on most platforms.)
+		 */
+		data = ( ( void * ) image->data );
+		image->data = virt_to_user ( data );
+
+		DBG ( "Embedded image \"%s\": %zd bytes at %p\n",
+		      image->name, image->len, data );
+
+		if ( ( rc = register_image ( image ) ) != 0 ) {
+			DBG ( "Could not register embedded image \"%s\": "
+			      "%s\n", image->name, strerror ( rc ) );
+			return;
+		}
+	}
+
+	/* Select the first image */
+	image = &embedded_images[0];
+	if ( ( rc = image_select ( image ) ) != 0 ) {
+		DBG ( "Could not select embedded image \"%s\": %s\n",
+		      image->name, strerror ( rc ) );
+		return;
+	}
+}
+
+/** Embedded image initialisation function */
+struct init_fn embedded_init_fn __init_fn ( INIT_LATE ) = {
+	.initialise = embedded_init,
+};
diff --git a/roms/ipxe/src/image/png.c b/roms/ipxe/src/image/png.c
new file mode 100644
index 00000000..c1460855
--- /dev/null
+++ b/roms/ipxe/src/image/png.c
@@ -0,0 +1,1007 @@
+/*
+ * Copyright (C) 2014 Michael Brown <mbrown@fensystems.co.uk>.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation; either version 2 of the
+ * License, or any later version.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
+ * 02110-1301, USA.
+ */
+
+FILE_LICENCE ( GPL2_OR_LATER );
+
+#include <stdint.h>
+#include <stdlib.h>
+#include <string.h>
+#include <errno.h>
+#include <byteswap.h>
+#include <ipxe/umalloc.h>
+#include <ipxe/pixbuf.h>
+#include <ipxe/deflate.h>
+#include <ipxe/png.h>
+
+/** @file
+ *
+ * Portable Network Graphics (PNG) format
+ *
+ * The PNG format is defined in RFC 2083.
+ */
+
+/** PNG context */
+struct png_context {
+	/** Offset within image */
+	size_t offset;
+
+	/** Pixel buffer */
+	struct pixel_buffer *pixbuf;
+
+	/** Bit depth */
+	unsigned int depth;
+	/** Colour type */
+	unsigned int colour_type;
+	/** Number of channels */
+	unsigned int channels;
+	/** Number of interlace passes */
+	unsigned int passes;
+	/** Palette, in iPXE's pixel buffer format */
+	uint32_t palette[PNG_PALETTE_COUNT];
+
+	/** Decompression buffer for raw PNG data */
+	struct deflate_chunk raw;
+	/** Decompressor */
+	struct deflate deflate;
+};
+
+/** A PNG interlace pass */
+struct png_interlace {
+	/** Pass number */
+	unsigned int pass;
+	/** X starting indent */
+	unsigned int x_indent;
+	/** Y starting indent */
+	unsigned int y_indent;
+	/** X stride */
+	unsigned int x_stride;
+	/** Y stride */
+	unsigned int y_stride;
+	/** Width */
+	unsigned int width;
+	/** Height */
+	unsigned int height;
+};
+
+/** PNG file signature */
+static struct png_signature png_signature = PNG_SIGNATURE;
+
+/** Number of interlacing passes */
+static uint8_t png_interlace_passes[] = {
+	[PNG_INTERLACE_NONE] = 1,
+	[PNG_INTERLACE_ADAM7] = 7,
+};
+
+/**
+ * Transcribe PNG chunk type name (for debugging)
+ *
+ * @v type		Chunk type
+ * @ret name		Chunk type name
+ */
+static const char * png_type_name ( uint32_t type ) {
+	static union {
+		uint32_t type;
+		char name[ sizeof ( uint32_t ) + 1 /* NUL */ ];
+	} u;
+
+	u.type = type;
+	return u.name;
+}
+
+/**
+ * Calculate PNG interlace pass parameters
+ *
+ * @v png		PNG context
+ * @v pass		Pass number (0=first pass)
+ * @v interlace		Interlace pass to fill in
+ */
+static void png_interlace ( struct png_context *png, unsigned int pass,
+			    struct png_interlace *interlace ) {
+	unsigned int grid_width_log2;
+	unsigned int grid_height_log2;
+	unsigned int x_indent;
+	unsigned int y_indent;
+	unsigned int x_stride_log2;
+	unsigned int y_stride_log2;
+	unsigned int x_stride;
+	unsigned int y_stride;
+	unsigned int width;
+	unsigned int height;
+
+	/* Sanity check */
+	assert ( png->passes > 0 );
+
+	/* Store pass number */
+	interlace->pass = pass;
+
+	/* Calculate interlace grid dimensions */
+	grid_width_log2 = ( png->passes / 2 );
+	grid_height_log2 = ( ( png->passes - 1 ) / 2 );
+
+	/* Calculate starting indents */
+	interlace->x_indent = x_indent =
+		( ( pass & 1 ) ?
+		  ( 1 << ( grid_width_log2 - ( pass / 2 ) - 1 ) ) : 0 );
+	interlace->y_indent = y_indent =
+		( ( pass && ! ( pass & 1 ) ) ?
+		  ( 1 << ( grid_height_log2 - ( ( pass - 1 ) / 2 ) - 1 ) ) : 0);
+
+	/* Calculate strides */
+	x_stride_log2 = ( grid_width_log2 - ( pass / 2 ) );
+	y_stride_log2 =
+		( grid_height_log2 - ( pass ? ( ( pass - 1 ) / 2 ) : 0 ) );
+	interlace->x_stride = x_stride = ( 1 << x_stride_log2 );
+	interlace->y_stride = y_stride = ( 1 << y_stride_log2 );
+
+	/* Calculate pass dimensions */
+	width = png->pixbuf->width;
+	height = png->pixbuf->height;
+	interlace->width =
+		( ( width - x_indent + x_stride - 1 ) >> x_stride_log2 );
+	interlace->height =
+		( ( height - y_indent + y_stride - 1 ) >> y_stride_log2 );
+}
+
+/**
+ * Calculate PNG pixel length
+ *
+ * @v png		PNG context
+ * @ret pixel_len	Pixel length
+ */
+static unsigned int png_pixel_len ( struct png_context *png ) {
+
+	return ( ( ( png->channels * png->depth ) + 7 ) / 8 );
+}
+
+/**
+ * Calculate PNG scanline length
+ *
+ * @v png		PNG context
+ * @v interlace		Interlace pass
+ * @ret scanline_len	Scanline length (including filter byte)
+ */
+static size_t png_scanline_len ( struct png_context *png,
+				 struct png_interlace *interlace ) {
+
+	return ( 1 /* Filter byte */ +
+		 ( ( interlace->width * png->channels * png->depth ) + 7 ) / 8);
+}
+
+/**
+ * Handle PNG image header chunk
+ *
+ * @v image		PNG image
+ * @v png		PNG context
+ * @v len		Chunk length
+ * @ret rc		Return status code
+ */
+static int png_image_header ( struct image *image, struct png_context *png,
+			      size_t len ) {
+	struct png_image_header ihdr;
+	struct png_interlace interlace;
+	unsigned int pass;
+
+	/* Sanity check */
+	if ( len != sizeof ( ihdr ) ) {
+		DBGC ( image, "PNG %s invalid IHDR length %zd\n",
+		       image->name, len );
+		return -EINVAL;
+	}
+	if ( png->pixbuf ) {
+		DBGC ( image, "PNG %s duplicate IHDR\n", image->name );
+		return -EINVAL;
+	}
+
+	/* Extract image header */
+	copy_from_user ( &ihdr, image->data, png->offset, len );
+	DBGC ( image, "PNG %s %dx%d depth %d type %d compression %d filter %d "
+	       "interlace %d\n", image->name, ntohl ( ihdr.width ),
+	       ntohl ( ihdr.height ), ihdr.depth, ihdr.colour_type,
+	       ihdr.compression, ihdr.filter, ihdr.interlace );
+
+	/* Sanity checks */
+	if ( ihdr.compression >= PNG_COMPRESSION_UNKNOWN ) {
+		DBGC ( image, "PNG %s unknown compression method %d\n",
+		       image->name, ihdr.compression );
+		return -ENOTSUP;
+	}
+	if ( ihdr.filter >= PNG_FILTER_UNKNOWN ) {
+		DBGC ( image, "PNG %s unknown filter method %d\n",
+		       image->name, ihdr.filter );
+		return -ENOTSUP;
+	}
+	if ( ihdr.interlace >= PNG_INTERLACE_UNKNOWN ) {
+		DBGC ( image, "PNG %s unknown interlace method %d\n",
+		       image->name, ihdr.interlace );
+		return -ENOTSUP;
+	}
+
+	/* Allocate pixel buffer */
+	png->pixbuf = alloc_pixbuf ( ntohl ( ihdr.width ),
+				     ntohl ( ihdr.height ) );
+	if ( ! png->pixbuf ) {
+		DBGC ( image, "PNG %s could not allocate pixel buffer\n",
+		       image->name );
+		return -ENOMEM;
+	}
+
+	/* Extract bit depth */
+	png->depth = ihdr.depth;
+	if ( ( png->depth == 0 ) ||
+	     ( ( png->depth & ( png->depth - 1 ) ) != 0 ) ) {
+		DBGC ( image, "PNG %s invalid depth %d\n",
+		       image->name, png->depth );
+		return -EINVAL;
+	}
+
+	/* Calculate number of channels */
+	png->colour_type = ihdr.colour_type;
+	png->channels = 1;
+	if ( ! ( ihdr.colour_type & PNG_COLOUR_TYPE_PALETTE ) ) {
+		if ( ihdr.colour_type & PNG_COLOUR_TYPE_RGB )
+			png->channels += 2;
+		if ( ihdr.colour_type & PNG_COLOUR_TYPE_ALPHA )
+			png->channels += 1;
+	}
+
+	/* Calculate number of interlace passes */
+	png->passes = png_interlace_passes[ihdr.interlace];
+
+	/* Calculate length of raw data buffer */
+	for ( pass = 0 ; pass < png->passes ; pass++ ) {
+		png_interlace ( png, pass, &interlace );
+		if ( interlace.width == 0 )
+			continue;
+		png->raw.len += ( interlace.height *
+				  png_scanline_len ( png, &interlace ) );
+	}
+
+	/* Allocate raw data buffer */
+	png->raw.data = umalloc ( png->raw.len );
+	if ( ! png->raw.data ) {
+		DBGC ( image, "PNG %s could not allocate data buffer\n",
+		       image->name );
+		return -ENOMEM;
+	}
+
+	return 0;
+}
+
+/**
+ * Handle PNG palette chunk
+ *
+ * @v image		PNG image
+ * @v png		PNG context
+ * @v len		Chunk length
+ * @ret rc		Return status code
+ */
+static int png_palette ( struct image *image, struct png_context *png,
+			 size_t len ) {
+	size_t offset = png->offset;
+	struct png_palette_entry palette;
+	unsigned int i;
+
+	/* Populate palette */
+	for ( i = 0 ; i < ( sizeof ( png->palette ) /
+			    sizeof ( png->palette[0] ) ) ; i++ ) {
+
+		/* Stop when we run out of palette data */
+		if ( len < sizeof ( palette ) )
+			break;
+
+		/* Extract palette entry */
+		copy_from_user ( &palette, image->data, offset,
+				 sizeof ( palette ) );
+		png->palette[i] = ( ( palette.red << 16 ) |
+				    ( palette.green << 8 ) |
+				    ( palette.blue << 0 ) );
+		DBGC2 ( image, "PNG %s palette entry %d is %#06x\n",
+			image->name, i, png->palette[i] );
+
+		/* Move to next entry */
+		offset += sizeof ( palette );
+		len -= sizeof ( palette );
+	}
+
+	return 0;
+}
+
+/**
+ * Handle PNG image data chunk
+ *
+ * @v image		PNG image
+ * @v png		PNG context
+ * @v len		Chunk length
+ * @ret rc		Return status code
+ */
+static int png_image_data ( struct image *image, struct png_context *png,
+			    size_t len ) {
+	struct deflate_chunk in;
+	int rc;
+
+	/* Deflate this chunk */
+	deflate_chunk_init ( &in, image->data, png->offset,
+			     ( png->offset + len ) );
+	if ( ( rc = deflate_inflate ( &png->deflate, &in, &png->raw ) ) != 0 ) {
+		DBGC ( image, "PNG %s could not decompress: %s\n",
+		       image->name, strerror ( rc ) );
+		return rc;
+	}
+
+	return 0;
+}
+
+/**
+ * Unfilter byte using the "None" filter
+ *
+ * @v current		Filtered current byte
+ * @v left		Unfiltered left byte
+ * @v above		Unfiltered above byte
+ * @v above_left	Unfiltered above-left byte
+ * @ret current		Unfiltered current byte
+ */
+static unsigned int png_unfilter_none ( unsigned int current,
+					unsigned int left __unused,
+					unsigned int above __unused,
+					unsigned int above_left __unused ) {
+
+	return current;
+}
+
+/**
+ * Unfilter byte using the "Sub" filter
+ *
+ * @v current		Filtered current byte
+ * @v left		Unfiltered left byte
+ * @v above		Unfiltered above byte
+ * @v above_left	Unfiltered above-left byte
+ * @ret current		Unfiltered current byte
+ */
+static unsigned int png_unfilter_sub ( unsigned int current,
+				       unsigned int left,
+				       unsigned int above __unused,
+				       unsigned int above_left __unused ) {
+
+	return ( current + left );
+}
+
+/**
+ * Unfilter byte using the "Up" filter
+ *
+ * @v current		Filtered current byte
+ * @v left		Unfiltered left byte
+ * @v above		Unfiltered above byte
+ * @v above_left	Unfiltered above-left byte
+ * @ret current		Unfiltered current byte
+ */
+static unsigned int png_unfilter_up ( unsigned int current,
+				      unsigned int left __unused,
+				      unsigned int above,
+				      unsigned int above_left __unused ) {
+
+	return ( current + above );
+}
+
+/**
+ * Unfilter byte using the "Average" filter
+ *
+ * @v current		Filtered current byte
+ * @v left		Unfiltered left byte
+ * @v above		Unfiltered above byte
+ * @v above_left	Unfiltered above-left byte
+ * @ret current		Unfiltered current byte
+ */
+static unsigned int png_unfilter_average ( unsigned int current,
+					   unsigned int left,
+					   unsigned int above,
+					   unsigned int above_left __unused ) {
+
+	return ( current + ( ( above + left ) >> 1 ) );
+}
+
+/**
+ * Paeth predictor function (defined in RFC 2083)
+ *
+ * @v a			Pixel A
+ * @v b			Pixel B
+ * @v c			Pixel C
+ * @ret predictor	Predictor pixel
+ */
+static unsigned int png_paeth_predictor ( unsigned int a, unsigned int b,
+					  unsigned int c ) {
+	unsigned int p;
+	unsigned int pa;
+	unsigned int pb;
+	unsigned int pc;
+
+	/* Algorithm as defined in RFC 2083 section 6.6 */
+	p = ( a + b - c );
+	pa = abs ( p - a );
+	pb = abs ( p - b );
+	pc = abs ( p - c );
+	if ( ( pa <= pb ) && ( pa <= pc ) ) {
+		return a;
+	} else if ( pb <= pc ) {
+		return b;
+	} else {
+		return c;
+	}
+}
+
+/**
+ * Unfilter byte using the "Paeth" filter
+ *
+ * @v current		Filtered current byte
+ * @v above_left	Unfiltered above-left byte
+ * @v above		Unfiltered above byte
+ * @v left		Unfiltered left byte
+ * @ret current		Unfiltered current byte
+ */
+static unsigned int png_unfilter_paeth ( unsigned int current,
+					 unsigned int left,
+					 unsigned int above,
+					 unsigned int above_left ) {
+
+	return ( current + png_paeth_predictor ( left, above, above_left ) );
+}
+
+/** A PNG filter */
+struct png_filter {
+	/**
+	 * Unfilter byte
+	 *
+	 * @v current		Filtered current byte
+	 * @v left		Unfiltered left byte
+	 * @v above		Unfiltered above byte
+	 * @v above_left	Unfiltered above-left byte
+	 * @ret current		Unfiltered current byte
+	 */
+	unsigned int ( * unfilter ) ( unsigned int current,
+				      unsigned int left,
+				      unsigned int above,
+				      unsigned int above_left );
+};
+
+/** PNG filter types */
+static struct png_filter png_filters[] = {
+	[PNG_FILTER_BASIC_NONE] = { png_unfilter_none },
+	[PNG_FILTER_BASIC_SUB] = { png_unfilter_sub },
+	[PNG_FILTER_BASIC_UP] = { png_unfilter_up },
+	[PNG_FILTER_BASIC_AVERAGE] = { png_unfilter_average },
+	[PNG_FILTER_BASIC_PAETH] = { png_unfilter_paeth },
+};
+
+/**
+ * Unfilter one interlace pass of PNG raw data
+ *
+ * @v image		PNG image
+ * @v png		PNG context
+ * @v interlace		Interlace pass
+ * @ret rc		Return status code
+ *
+ * This routine may assume that it is impossible to overrun the raw
+ * data buffer, since the size is determined by the image dimensions.
+ */
+static int png_unfilter_pass ( struct image *image, struct png_context *png,
+			       struct png_interlace *interlace ) {
+	size_t offset = png->raw.offset;
+	size_t pixel_len = png_pixel_len ( png );
+	size_t scanline_len = png_scanline_len ( png, interlace );
+	struct png_filter *filter;
+	unsigned int scanline;
+	unsigned int byte;
+	uint8_t filter_type;
+	uint8_t left;
+	uint8_t above;
+	uint8_t above_left;
+	uint8_t current;
+
+	/* On the first scanline of a pass, above bytes are assumed to
+	 * be zero.
+	 */
+	above = 0;
+
+	/* Iterate over each scanline in turn */
+	for ( scanline = 0 ; scanline < interlace->height ; scanline++ ) {
+
+		/* Extract filter byte and determine filter type */
+		copy_from_user ( &filter_type, png->raw.data, offset++,
+				 sizeof ( filter_type ) );
+		if ( filter_type >= ( sizeof ( png_filters ) /
+				      sizeof ( png_filters[0] ) ) ) {
+			DBGC ( image, "PNG %s unknown filter type %d\n",
+			       image->name, filter_type );
+			return -ENOTSUP;
+		}
+		filter = &png_filters[filter_type];
+		assert ( filter->unfilter != NULL );
+		DBGC2 ( image, "PNG %s pass %d scanline %d filter type %d\n",
+			image->name, interlace->pass, scanline, filter_type );
+
+		/* At the start of a line, both above-left and left
+		 * bytes are taken to be zero.
+		 */
+		left = 0;
+		above_left = 0;
+
+		/* Iterate over each byte (not pixel) in turn */
+		for ( byte = 0 ; byte < ( scanline_len - 1 ) ; byte++ ) {
+
+			/* Extract predictor bytes, if applicable */
+			if ( byte >= pixel_len ) {
+				copy_from_user ( &left, png->raw.data,
+						 ( offset - pixel_len ),
+						 sizeof ( left ) );
+			}
+			if ( scanline > 0 ) {
+				copy_from_user ( &above, png->raw.data,
+						 ( offset - scanline_len ),
+						 sizeof ( above ) );
+			}
+			if ( ( scanline > 0 ) && ( byte >= pixel_len ) ) {
+				copy_from_user ( &above_left, png->raw.data,
+						 ( offset - scanline_len -
+						   pixel_len ),
+						 sizeof ( above_left ) );
+			}
+
+			/* Unfilter current byte */
+			copy_from_user ( &current, png->raw.data,
+					 offset, sizeof ( current ) );
+			current = filter->unfilter ( current, left, above,
+						     above_left );
+			copy_to_user ( png->raw.data, offset++,
+				       &current, sizeof ( current ) );
+		}
+	}
+
+	/* Update offset */
+	png->raw.offset = offset;
+
+	return 0;
+}
+
+/**
+ * Unfilter PNG raw data
+ *
+ * @v image		PNG image
+ * @v png		PNG context
+ * @ret rc		Return status code
+ *
+ * This routine may assume that it is impossible to overrun the raw
+ * data buffer, since the size is determined by the image dimensions.
+ */
+static int png_unfilter ( struct image *image, struct png_context *png ) {
+	struct png_interlace interlace;
+	unsigned int pass;
+	int rc;
+
+	/* Process each interlace pass */
+	png->raw.offset = 0;
+	for ( pass = 0 ; pass < png->passes ; pass++ ) {
+
+		/* Calculate interlace pass parameters */
+		png_interlace ( png, pass, &interlace );
+
+		/* Skip zero-width rows (which have no filter bytes) */
+		if ( interlace.width == 0 )
+			continue;
+
+		/* Unfilter this pass */
+		if ( ( rc = png_unfilter_pass ( image, png,
+						&interlace ) ) != 0 )
+			return rc;
+	}
+	assert ( png->raw.offset == png->raw.len );
+
+	return 0;
+}
+
+/**
+ * Calculate PNG pixel component value
+ *
+ * @v raw		Raw component value
+ * @v alpha		Alpha value
+ * @v max		Maximum raw/alpha value
+ * @ret value		Component value in range 0-255
+ */
+static inline unsigned int png_pixel ( unsigned int raw, unsigned int alpha,
+				       unsigned int max ) {
+
+	/* The basic calculation is 255*(raw/max)*(value/max).  We use
+	 * fixed-point arithmetic (scaling up to the maximum range for
+	 * a 32-bit integer), in order to get the same results for
+	 * alpha blending as the test cases (produced using
+	 * ImageMagick).
+	 */
+	return ( ( ( ( ( 0xff00 * raw * alpha ) / max ) / max ) + 0x80 ) >> 8 );
+}
+
+/**
+ * Fill one interlace pass of PNG pixels
+ *
+ * @v image		PNG image
+ * @v png		PNG context
+ * @v interlace		Interlace pass
+ *
+ * This routine may assume that it is impossible to overrun either the
+ * raw data buffer or the pixel buffer, since the sizes of both are
+ * determined by the image dimensions.
+ */
+static void png_pixels_pass ( struct image *image,
+			      struct png_context *png,
+			      struct png_interlace *interlace ) {
+	size_t raw_offset = png->raw.offset;
+	uint8_t channel[png->channels];
+	int is_indexed = ( png->colour_type & PNG_COLOUR_TYPE_PALETTE );
+	int is_rgb = ( png->colour_type & PNG_COLOUR_TYPE_RGB );
+	int has_alpha = ( png->colour_type & PNG_COLOUR_TYPE_ALPHA );
+	size_t pixbuf_y_offset;
+	size_t pixbuf_offset;
+	size_t pixbuf_x_stride;
+	size_t pixbuf_y_stride;
+	size_t raw_stride;
+	unsigned int y;
+	unsigned int x;
+	unsigned int c;
+	unsigned int bits;
+	unsigned int depth;
+	unsigned int max;
+	unsigned int alpha;
+	unsigned int raw;
+	unsigned int value;
+	uint8_t current = 0;
+	uint32_t pixel;
+
+	/* We only ever use the top byte of 16-bit pixels.  Model this
+	 * as a bit depth of 8 with a stride of more than one.
+	 */
+	depth = png->depth;
+	raw_stride = ( ( depth + 7 ) / 8 );
+	if ( depth > 8 )
+		depth = 8;
+	max = ( ( 1 << depth ) - 1 );
+
+	/* Calculate pixel buffer offset and strides */
+	pixbuf_y_offset = ( ( ( interlace->y_indent * png->pixbuf->width ) +
+			      interlace->x_indent ) * sizeof ( pixel ) );
+	pixbuf_x_stride = ( interlace->x_stride * sizeof ( pixel ) );
+	pixbuf_y_stride = ( interlace->y_stride * png->pixbuf->width *
+			    sizeof ( pixel ) );
+	DBGC2 ( image, "PNG %s pass %d %dx%d at (%d,%d) stride (%d,%d)\n",
+		image->name, interlace->pass, interlace->width,
+		interlace->height, interlace->x_indent, interlace->y_indent,
+		interlace->x_stride, interlace->y_stride );
+
+	/* Iterate over each scanline in turn */
+	for ( y = 0 ; y < interlace->height ; y++ ) {
+
+		/* Skip filter byte */
+		raw_offset++;
+
+		/* Iterate over each pixel in turn */
+		bits = depth;
+		pixbuf_offset = pixbuf_y_offset;
+		for ( x = 0 ; x < interlace->width ; x++ ) {
+
+			/* Extract sample value */
+			for ( c = 0 ; c < png->channels ; c++ ) {
+
+				/* Get sample value into high bits of current */
+				current <<= depth;
+				bits -= depth;
+				if ( ! bits ) {
+					copy_from_user ( &current,
+							 png->raw.data,
+							 raw_offset,
+							 sizeof ( current ) );
+					raw_offset += raw_stride;
+					bits = 8;
+				}
+
+				/* Extract sample value */
+				channel[c] = ( current >> ( 8 - depth ) );
+			}
+
+			/* Convert to native pixel format */
+			if ( is_indexed ) {
+
+				/* Indexed */
+				pixel = png->palette[channel[0]];
+
+			} else {
+
+				/* Determine alpha value */
+				alpha = ( has_alpha ?
+					  channel[ png->channels - 1 ] : max );
+
+				/* Convert to RGB value */
+				pixel = 0;
+				for ( c = 0 ; c < 3 ; c++ ) {
+					raw = channel[ is_rgb ? c : 0 ];
+					value = png_pixel ( raw, alpha, max );
+					assert ( value <= 255 );
+					pixel = ( ( pixel << 8 ) | value );
+				}
+			}
+
+			/* Store pixel */
+			copy_to_user ( png->pixbuf->data, pixbuf_offset,
+				       &pixel, sizeof ( pixel ) );
+			pixbuf_offset += pixbuf_x_stride;
+		}
+
+		/* Move to next output row */
+		pixbuf_y_offset += pixbuf_y_stride;
+	}
+
+	/* Update offset */
+	png->raw.offset = raw_offset;
+}
+
+/**
+ * Fill PNG pixels
+ *
+ * @v image		PNG image
+ * @v png		PNG context
+ *
+ * This routine may assume that it is impossible to overrun either the
+ * raw data buffer or the pixel buffer, since the sizes of both are
+ * determined by the image dimensions.
+ */
+static void png_pixels ( struct image *image, struct png_context *png ) {
+	struct png_interlace interlace;
+	unsigned int pass;
+
+	/* Process each interlace pass */
+	png->raw.offset = 0;
+	for ( pass = 0 ; pass < png->passes ; pass++ ) {
+
+		/* Calculate interlace pass parameters */
+		png_interlace ( png, pass, &interlace );
+
+		/* Skip zero-width rows (which have no filter bytes) */
+		if ( interlace.width == 0 )
+			continue;
+
+		/* Unfilter this pass */
+		png_pixels_pass ( image, png, &interlace );
+	}
+	assert ( png->raw.offset == png->raw.len );
+}
+
+/**
+ * Handle PNG image end chunk
+ *
+ * @v image		PNG image
+ * @v png		PNG context
+ * @v len		Chunk length
+ * @ret rc		Return status code
+ */
+static int png_image_end ( struct image *image, struct png_context *png,
+			   size_t len ) {
+	int rc;
+
+	/* Sanity checks */
+	if ( len != 0 ) {
+		DBGC ( image, "PNG %s invalid IEND length %zd\n",
+		       image->name, len );
+		return -EINVAL;
+	}
+	if ( ! png->pixbuf ) {
+		DBGC ( image, "PNG %s missing pixel buffer (no IHDR?)\n",
+		       image->name );
+		return -EINVAL;
+	}
+	if ( ! deflate_finished ( &png->deflate ) ) {
+		DBGC ( image, "PNG %s decompression not complete\n",
+		       image->name );
+		return -EINVAL;
+	}
+	if ( png->raw.offset != png->raw.len ) {
+		DBGC ( image, "PNG %s incorrect decompressed length (expected "
+		       "%zd, got %zd)\n", image->name, png->raw.len,
+		       png->raw.offset );
+		return -EINVAL;
+	}
+
+	/* Unfilter raw data */
+	if ( ( rc = png_unfilter ( image, png ) ) != 0 )
+		return rc;
+
+	/* Fill pixel buffer */
+	png_pixels ( image, png );
+
+	return 0;
+}
+
+/** A PNG chunk handler */
+struct png_chunk_handler {
+	/** Chunk type */
+	uint32_t type;
+	/**
+	 * Handle chunk
+	 *
+	 * @v image		PNG image
+	 * @v png		PNG context
+	 * @v len		Chunk length
+	 * @ret rc		Return status code
+	 */
+	int ( * handle ) ( struct image *image, struct png_context *png,
+			   size_t len );
+};
+
+/** PNG chunk handlers */
+static struct png_chunk_handler png_chunk_handlers[] = {
+	{ htonl ( PNG_TYPE_IHDR ), png_image_header },
+	{ htonl ( PNG_TYPE_PLTE ), png_palette },
+	{ htonl ( PNG_TYPE_IDAT ), png_image_data },
+	{ htonl ( PNG_TYPE_IEND ), png_image_end },
+};
+
+/**
+ * Handle PNG chunk
+ *
+ * @v image		PNG image
+ * @v png		PNG context
+ * @v type		Chunk type
+ * @v len		Chunk length
+ * @ret rc		Return status code
+ */
+static int png_chunk ( struct image *image, struct png_context *png,
+		       uint32_t type, size_t len ) {
+	struct png_chunk_handler *handler;
+	unsigned int i;
+
+	DBGC ( image, "PNG %s chunk type %s offset %zd length %zd\n",
+	       image->name, png_type_name ( type ), png->offset, len );
+
+	/* Handle according to chunk type */
+	for ( i = 0 ; i < ( sizeof ( png_chunk_handlers ) /
+			    sizeof ( png_chunk_handlers[0] ) ) ; i++ ) {
+		handler = &png_chunk_handlers[i];
+		if ( handler->type == type )
+			return handler->handle ( image, png, len );
+	}
+
+	/* Fail if unknown chunk type is critical */
+	if ( ! ( type & htonl ( PNG_CHUNK_ANCILLARY ) ) ) {
+		DBGC ( image, "PNG %s unknown critical chunk type %s\n",
+		       image->name, png_type_name ( type ) );
+		return -ENOTSUP;
+	}
+
+	/* Ignore non-critical unknown chunk types */
+	return 0;
+}
+
+/**
+ * Convert PNG image to pixel buffer
+ *
+ * @v image		PNG image
+ * @v pixbuf		Pixel buffer to fill in
+ * @ret rc		Return status code
+ */
+static int png_pixbuf ( struct image *image, struct pixel_buffer **pixbuf ) {
+	struct png_context *png;
+	struct png_chunk_header header;
+	struct png_chunk_footer footer;
+	size_t remaining;
+	size_t chunk_len;
+	int rc;
+
+	/* Allocate and initialise context */
+	png = zalloc ( sizeof ( *png ) );
+	if ( ! png ) {
+		rc = -ENOMEM;
+		goto err_alloc;
+	}
+	png->offset = sizeof ( struct png_signature );
+	deflate_init ( &png->deflate, DEFLATE_ZLIB );
+
+	/* Process chunks */
+	do {
+
+		/* Extract chunk header */
+		remaining = ( image->len - png->offset );
+		if ( remaining < sizeof ( header ) ) {
+			DBGC ( image, "PNG %s truncated chunk header at offset "
+			       "%zd\n", image->name, png->offset );
+			rc = -EINVAL;
+			goto err_truncated;
+		}
+		copy_from_user ( &header, image->data, png->offset,
+				 sizeof ( header ) );
+		png->offset += sizeof ( header );
+
+		/* Validate chunk length */
+		chunk_len = ntohl ( header.len );
+		if ( remaining < ( sizeof ( header ) + chunk_len +
+				   sizeof ( footer ) ) ) {
+			DBGC ( image, "PNG %s truncated chunk data/footer at "
+			       "offset %zd\n", image->name, png->offset );
+			rc = -EINVAL;
+			goto err_truncated;
+		}
+
+		/* Handle chunk */
+		if ( ( rc = png_chunk ( image, png, header.type,
+					chunk_len ) ) != 0 )
+			goto err_chunk;
+
+		/* Move to next chunk */
+		png->offset += ( chunk_len + sizeof ( footer ) );
+
+	} while ( png->offset < image->len );
+
+	/* Check that we finished with an IEND chunk */
+	if ( header.type != htonl ( PNG_TYPE_IEND ) ) {
+		DBGC ( image, "PNG %s did not finish with IEND\n",
+		       image->name );
+		rc = -EINVAL;
+		goto err_iend;
+	}
+
+	/* Return pixel buffer */
+	*pixbuf = pixbuf_get ( png->pixbuf );
+
+	/* Success */
+	rc = 0;
+
+ err_iend:
+ err_chunk:
+ err_truncated:
+	pixbuf_put ( png->pixbuf );
+	ufree ( png->raw.data );
+	free ( png );
+ err_alloc:
+	return rc;
+}
+
+/**
+ * Probe PNG image
+ *
+ * @v image		PNG image
+ * @ret rc		Return status code
+ */
+static int png_probe ( struct image *image ) {
+	struct png_signature signature;
+
+	/* Sanity check */
+	if ( image->len < sizeof ( signature ) ) {
+		DBGC ( image, "PNG %s is too short\n", image->name );
+		return -ENOEXEC;
+	}
+
+	/* Check signature */
+	copy_from_user ( &signature, image->data, 0, sizeof ( signature ) );
+	if ( memcmp ( &signature, &png_signature, sizeof ( signature ) ) != 0 ){
+		DBGC ( image, "PNG %s has invalid signature\n", image->name );
+		return -ENOEXEC;
+	}
+
+	return 0;
+}
+
+/** PNG image type */
+struct image_type png_image_type __image_type ( PROBE_NORMAL ) = {
+	.name = "PNG",
+	.probe = png_probe,
+	.pixbuf = png_pixbuf,
+};
diff --git a/roms/ipxe/src/image/pnm.c b/roms/ipxe/src/image/pnm.c
new file mode 100644
index 00000000..af9e571a
--- /dev/null
+++ b/roms/ipxe/src/image/pnm.c
@@ -0,0 +1,415 @@
+/*
+ * Copyright (C) 2013 Michael Brown <mbrown@fensystems.co.uk>.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation; either version 2 of the
+ * License, or any later version.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
+ * 02110-1301, USA.
+ */
+
+FILE_LICENCE ( GPL2_OR_LATER );
+
+/** @file
+ *
+ * Portable anymap format (PNM)
+ *
+ */
+
+#include <stdlib.h>
+#include <errno.h>
+#include <ctype.h>
+#include <ipxe/image.h>
+#include <ipxe/pixbuf.h>
+#include <ipxe/pnm.h>
+
+/**
+ * Extract PNM ASCII value
+ *
+ * @v image		PNM image
+ * @v pnm		PNM context
+ * @ret value		Value, or negative error
+ */
+static int pnm_ascii ( struct image *image, struct pnm_context *pnm ) {
+	char buf[ pnm->ascii_len + 1 /* NUL */ ];
+	char *endp;
+	size_t len;
+	int value;
+	int in_comment = 0;
+
+	/* Skip any leading whitespace and comments */
+	for ( ; pnm->offset < image->len ; pnm->offset++ ) {
+		copy_from_user ( &buf[0], image->data, pnm->offset,
+				 sizeof ( buf[0] ) );
+		if ( in_comment ) {
+			if ( buf[0] == '\n' )
+				in_comment = 0;
+		} else {
+			if ( buf[0] == '#' ) {
+				in_comment = 1;
+			} else if ( ! isspace ( buf[0] ) ) {
+				break;
+			}
+		}
+	}
+
+	/* Fail if no value is present */
+	len = ( image->len - pnm->offset );
+	if ( len == 0 ) {
+		DBGC ( image, "PNM %s ran out of ASCII data\n", image->name );
+		return -EINVAL;
+	}
+
+	/* Copy ASCII value to buffer and ensure string is NUL-terminated */
+	if ( len > ( sizeof ( buf ) - 1 /* NUL */ ) )
+		len = ( sizeof ( buf ) - 1 /* NUL */ );
+	copy_from_user ( buf, image->data, pnm->offset, len );
+	buf[len] = '\0';
+
+	/* Parse value and update offset */
+	value = strtoul ( buf, &endp, 0 );
+	pnm->offset += ( endp - buf );
+
+	/* Check and skip terminating whitespace character, if present */
+	if ( ( pnm->offset != image->len ) && ( *endp != '\0' ) ) {
+		if ( ! isspace ( *endp ) ) {
+			DBGC ( image, "PNM %s invalid ASCII integer\n",
+			       image->name );
+			return -EINVAL;
+		}
+		pnm->offset++;
+	}
+
+	return value;
+}
+
+/**
+ * Extract PNM binary value
+ *
+ * @v image		PNM image
+ * @v pnm		PNM context
+ * @ret value		Value, or negative error
+ */
+static int pnm_binary ( struct image *image, struct pnm_context *pnm ) {
+	uint8_t value;
+
+	/* Sanity check */
+	if ( pnm->offset == image->len ) {
+		DBGC ( image, "PNM %s ran out of binary data\n",
+		       image->name );
+		return -EINVAL;
+	}
+
+	/* Extract value */
+	copy_from_user ( &value, image->data, pnm->offset, sizeof ( value ) );
+	pnm->offset++;
+
+	return value;
+}
+
+/**
+ * Scale PNM scalar value
+ *
+ * @v image		PNM image
+ * @v pnm		PNM context
+ * @v value		Raw value
+ * @ret value		Scaled value (in range 0-255)
+ */
+static int pnm_scale ( struct image *image, struct pnm_context *pnm,
+		       unsigned int value ) {
+
+	if ( value > pnm->max ) {
+		DBGC ( image, "PNM %s has out-of-range value %d (max %d)\n",
+		       image->name, value, pnm->max );
+		return -EINVAL;
+	}
+	return ( ( 255 * value ) / pnm->max );
+}
+
+/**
+ * Convert PNM bitmap composite value to RGB
+ *
+ * @v composite		Composite value
+ * @v index		Pixel index within this composite value
+ * @ret rgb		24-bit RGB value
+ */
+static uint32_t pnm_bitmap ( uint32_t composite, unsigned int index ) {
+
+	/* Composite value is an 8-bit bitmask */
+	return ( ( ( composite << index ) & 0x80 ) ? 0x000000 : 0xffffff );
+}
+
+/**
+ * Convert PNM greymap composite value to RGB
+ *
+ * @v composite		Composite value
+ * @v index		Pixel index within this composite value
+ * @ret rgb		24-bit RGB value
+ */
+static uint32_t pnm_greymap ( uint32_t composite, unsigned int index __unused ){
+
+	/* Composite value is an 8-bit greyscale value */
+	return ( ( composite << 16 ) | ( composite << 8 ) | composite );
+}
+
+/**
+ * Convert PNM pixmap composite value to RGB
+ *
+ * @v composite		Composite value
+ * @v index		Pixel index within this composite value
+ * @ret rgb		24-bit RGB value
+ */
+static uint32_t pnm_pixmap ( uint32_t composite, unsigned int index __unused ) {
+
+	/* Composite value is already an RGB value */
+	return composite;
+}
+
+/**
+ * Extract PNM pixel data
+ *
+ * @v image		PNM image
+ * @v pnm		PNM context
+ * @v pixbuf		Pixel buffer
+ * @ret rc		Return status code
+ */
+static int pnm_data ( struct image *image, struct pnm_context *pnm,
+		      struct pixel_buffer *pixbuf ) {
+	struct pnm_type *type = pnm->type;
+	size_t offset = 0;
+	unsigned int xpos = 0;
+	int scalar;
+	uint32_t composite;
+	uint32_t rgb;
+	unsigned int i;
+
+	/* Fill pixel buffer */
+	while ( offset < pixbuf->len ) {
+
+		/* Extract a scaled composite scalar value from the file */
+		composite = 0;
+		for ( i = 0 ; i < type->depth ; i++ ) {
+			scalar = type->scalar ( image, pnm );
+			if ( scalar < 0 )
+				return scalar;
+			scalar = pnm_scale ( image, pnm, scalar );
+			if ( scalar < 0 )
+				return scalar;
+			composite = ( ( composite << 8 ) | scalar );
+		}
+
+		/* Extract 24-bit RGB values from composite value */
+		for ( i = 0 ; i < type->packing ; i++ ) {
+			if ( offset >= pixbuf->len ) {
+				DBGC ( image, "PNM %s has too many pixels\n",
+				       image->name );
+				return -EINVAL;
+			}
+			rgb = type->rgb ( composite, i );
+			copy_to_user ( pixbuf->data, offset, &rgb,
+				       sizeof ( rgb ) );
+			offset += sizeof ( rgb );
+			if ( ++xpos == pixbuf->width ) {
+				xpos = 0;
+				break;
+			}
+		}
+	}
+
+	return 0;
+}
+
+/** PNM image types */
+static struct pnm_type pnm_types[] = {
+	{
+		.type = '1',
+		.depth = 1,
+		.packing = 1,
+		.flags = PNM_BITMAP,
+		.scalar = pnm_ascii,
+		.rgb = pnm_bitmap,
+	},
+	{
+		.type = '2',
+		.depth = 1,
+		.packing = 1,
+		.scalar = pnm_ascii,
+		.rgb = pnm_greymap,
+	},
+	{
+		.type = '3',
+		.depth = 3,
+		.packing = 1,
+		.scalar = pnm_ascii,
+		.rgb = pnm_pixmap,
+	},
+	{
+		.type = '4',
+		.depth = 1,
+		.packing = 8,
+		.flags = PNM_BITMAP,
+		.scalar = pnm_binary,
+		.rgb = pnm_bitmap,
+	},
+	{
+		.type = '5',
+		.depth = 1,
+		.packing = 1,
+		.scalar = pnm_binary,
+		.rgb = pnm_greymap,
+	},
+	{
+		.type = '6',
+		.depth = 3,
+		.packing = 1,
+		.scalar = pnm_binary,
+		.rgb = pnm_pixmap,
+	},
+};
+
+/**
+ * Determine PNM image type
+ *
+ * @v image		PNM image
+ * @ret type		PNM image type, or NULL if not found
+ */
+static struct pnm_type * pnm_type ( struct image *image ) {
+	struct pnm_signature signature;
+	struct pnm_type *type;
+	unsigned int i;
+
+	/* Extract signature */
+	assert ( image->len >= sizeof ( signature ) );
+	copy_from_user ( &signature, image->data, 0, sizeof ( signature ) );
+
+	/* Check for supported types */
+	for ( i = 0 ; i < ( sizeof ( pnm_types ) /
+			    sizeof ( pnm_types[0] ) ) ; i++ ) {
+		type = &pnm_types[i];
+		if ( type->type == signature.type )
+			return type;
+	}
+	return NULL;
+}
+
+/**
+ * Convert PNM image to pixel buffer
+ *
+ * @v image		PNM image
+ * @v pixbuf		Pixel buffer to fill in
+ * @ret rc		Return status code
+ */
+static int pnm_pixbuf ( struct image *image, struct pixel_buffer **pixbuf ) {
+	struct pnm_context pnm;
+	int width;
+	int height;
+	int max;
+	int rc;
+
+	/* Initialise PNM context */
+	pnm.type = pnm_type ( image );
+	if ( ! pnm.type ) {
+		rc = -ENOTSUP;
+		goto err_type;
+	}
+	pnm.offset = sizeof ( struct pnm_signature );
+	pnm.ascii_len = PNM_ASCII_LEN;
+
+	/* Extract width */
+	if ( ( width = pnm_ascii ( image, &pnm ) ) < 0 ) {
+		rc = width;
+		goto err_width;
+	}
+
+	/* Extract height */
+	if ( ( height = pnm_ascii ( image, &pnm ) ) < 0 ) {
+		rc = height;
+		goto err_height;
+	}
+
+	/* Extract maximum scalar value, if not predefined */
+	if ( pnm.type->flags & PNM_BITMAP ) {
+		pnm.max = ( ( 1 << pnm.type->packing ) - 1 );
+		pnm.ascii_len = 1;
+	} else {
+		if ( ( max = pnm_ascii ( image, &pnm ) ) < 0 ) {
+			rc = max;
+			goto err_max;
+		}
+		pnm.max = max;
+	}
+	if ( pnm.max == 0 ) {
+		DBGC ( image, "PNM %s has invalid maximum value 0\n",
+		       image->name );
+		rc = -EINVAL;
+		goto err_max;
+	}
+	DBGC ( image, "PNM %s is type %c width %d height %d max %d\n",
+	       image->name, pnm.type->type, width, height, pnm.max );
+
+	/* Allocate pixel buffer */
+	*pixbuf = alloc_pixbuf ( width, height );
+	if ( ! *pixbuf ) {
+		rc = -ENOMEM;
+		goto err_alloc_pixbuf;
+	}
+
+	/* Extract pixel data */
+	if ( ( rc = pnm_data ( image, &pnm, *pixbuf ) ) != 0 )
+		goto err_data;
+
+	return 0;
+
+ err_data:
+	pixbuf_put ( *pixbuf );
+ err_alloc_pixbuf:
+ err_max:
+ err_height:
+ err_width:
+ err_type:
+	return rc;
+}
+
+/**
+ * Probe PNM image
+ *
+ * @v image		PNM image
+ * @ret rc		Return status code
+ */
+static int pnm_probe ( struct image *image ) {
+	struct pnm_signature signature;
+
+	/* Sanity check */
+	if ( image->len < sizeof ( signature ) ) {
+		DBGC ( image, "PNM %s is too short\n", image->name );
+		return -ENOEXEC;
+	}
+
+	/* Check signature */
+	copy_from_user ( &signature, image->data, 0, sizeof ( signature ) );
+	if ( ! ( ( signature.magic == PNM_MAGIC ) &&
+		 ( isdigit ( signature.type ) ) &&
+		 ( isspace ( signature.space ) ) ) ) {
+		DBGC ( image, "PNM %s has invalid signature\n", image->name );
+		return -ENOEXEC;
+	}
+	DBGC ( image, "PNM %s is type %c\n", image->name, signature.type );
+
+	return 0;
+}
+
+/** PNM image type */
+struct image_type pnm_image_type __image_type ( PROBE_NORMAL ) = {
+	.name = "PNM",
+	.probe = pnm_probe,
+	.pixbuf = pnm_pixbuf,
+};
diff --git a/roms/ipxe/src/image/script.c b/roms/ipxe/src/image/script.c
new file mode 100644
index 00000000..5328da8b
--- /dev/null
+++ b/roms/ipxe/src/image/script.c
@@ -0,0 +1,423 @@
+/*
+ * Copyright (C) 2007 Michael Brown <mbrown@fensystems.co.uk>.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation; either version 2 of the
+ * License, or any later version.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
+ * 02110-1301, USA.
+ */
+
+FILE_LICENCE ( GPL2_OR_LATER );
+
+/**
+ * @file
+ *
+ * iPXE scripts
+ *
+ */
+
+#include <string.h>
+#include <stdlib.h>
+#include <stdio.h>
+#include <ctype.h>
+#include <errno.h>
+#include <getopt.h>
+#include <ipxe/command.h>
+#include <ipxe/parseopt.h>
+#include <ipxe/image.h>
+#include <ipxe/shell.h>
+#include <usr/prompt.h>
+#include <ipxe/script.h>
+
+/** Offset within current script
+ *
+ * This is a global in order to allow goto_exec() to update the
+ * offset.
+ */
+static size_t script_offset;
+
+/**
+ * Process script lines
+ *
+ * @v image		Script
+ * @v process_line	Line processor
+ * @v terminate		Termination check
+ * @ret rc		Return status code
+ */
+static int process_script ( struct image *image,
+			    int ( * process_line ) ( struct image *image,
+						     size_t offset,
+						     const char *label,
+						     const char *command ),
+			    int ( * terminate ) ( int rc ) ) {
+	size_t len = 0;
+	char *line = NULL;
+	size_t line_offset;
+	char *label;
+	char *command;
+	off_t eol;
+	size_t frag_len;
+	char *tmp;
+	int rc;
+
+	/* Initialise script and line offsets */
+	script_offset = 0;
+	line_offset = 0;
+
+	do {
+
+		/* Find length of next line, excluding any terminating '\n' */
+		eol = memchr_user ( image->data, script_offset, '\n',
+				    ( image->len - script_offset ) );
+		if ( eol < 0 )
+			eol = image->len;
+		frag_len = ( eol - script_offset );
+
+		/* Allocate buffer for line */
+		tmp = realloc ( line, ( len + frag_len + 1 /* NUL */ ) );
+		if ( ! tmp ) {
+			rc = -ENOMEM;
+			goto err_alloc;
+		}
+		line = tmp;
+
+		/* Copy line */
+		copy_from_user ( ( line + len ), image->data, script_offset,
+				 frag_len );
+		len += frag_len;
+
+		/* Move to next line in script */
+		script_offset += ( frag_len + 1 );
+
+		/* Strip trailing CR, if present */
+		if ( len && ( line[ len - 1 ] == '\r' ) )
+			len--;
+
+		/* Handle backslash continuations */
+		if ( len && ( line[ len - 1 ] == '\\' ) ) {
+			len--;
+			rc = -EINVAL;
+			continue;
+		}
+
+		/* Terminate line */
+		line[len] = '\0';
+
+		/* Split line into (optional) label and command */
+		command = line;
+		while ( isspace ( *command ) )
+			command++;
+		if ( *command == ':' ) {
+			label = ++command;
+			while ( *command && ! isspace ( *command ) )
+				command++;
+			if ( *command )
+				*(command++) = '\0';
+		} else {
+			label = NULL;
+		}
+
+		/* Process line */
+		rc = process_line ( image, line_offset, label, command );
+		if ( terminate ( rc ) )
+			goto err_process;
+
+		/* Free line */
+		free ( line );
+		line = NULL;
+		len = 0;
+
+		/* Update line offset */
+		line_offset = script_offset;
+
+	} while ( script_offset < image->len );
+
+ err_process:
+ err_alloc:
+	free ( line );
+	return rc;
+}
+
+/**
+ * Terminate script processing on shell exit or command failure
+ *
+ * @v rc		Line processing status
+ * @ret terminate	Terminate script processing
+ */
+static int terminate_on_exit_or_failure ( int rc ) {
+
+	return ( shell_stopped ( SHELL_STOP_COMMAND_SEQUENCE ) ||
+		 ( rc != 0 ) );
+}
+
+/**
+ * Execute script line
+ *
+ * @v image		Script
+ * @v offset		Offset within script
+ * @v label		Label, or NULL
+ * @v command		Command
+ * @ret rc		Return status code
+ */
+static int script_exec_line ( struct image *image, size_t offset,
+			      const char *label __unused,
+			      const char *command ) {
+	int rc;
+
+	DBGC ( image, "[%04zx] $ %s\n", offset, command );
+
+	/* Execute command */
+	if ( ( rc = system ( command ) ) != 0 )
+		return rc;
+
+	return 0;
+}
+
+/**
+ * Execute script
+ *
+ * @v image		Script
+ * @ret rc		Return status code
+ */
+static int script_exec ( struct image *image ) {
+	size_t saved_offset;
+	int rc;
+
+	/* Temporarily de-register image, so that a "boot" command
+	 * doesn't throw us into an execution loop.
+	 */
+	unregister_image ( image );
+
+	/* Preserve state of any currently-running script */
+	saved_offset = script_offset;
+
+	/* Process script */
+	rc = process_script ( image, script_exec_line,
+			      terminate_on_exit_or_failure );
+
+	/* Restore saved state */
+	script_offset = saved_offset;
+
+	/* Re-register image (unless we have been replaced) */
+	if ( ! image->replacement )
+		register_image ( image );
+
+	return rc;
+}
+
+/**
+ * Probe script image
+ *
+ * @v image		Script
+ * @ret rc		Return status code
+ */
+static int script_probe ( struct image *image ) {
+	static const char ipxe_magic[] = "#!ipxe";
+	static const char gpxe_magic[] = "#!gpxe";
+	linker_assert ( sizeof ( ipxe_magic ) == sizeof ( gpxe_magic ),
+			magic_size_mismatch );
+	char test[ sizeof ( ipxe_magic ) - 1 /* NUL */
+		   + 1 /* terminating space */];
+
+	/* Sanity check */
+	if ( image->len < sizeof ( test ) ) {
+		DBGC ( image, "Too short to be a script\n" );
+		return -ENOEXEC;
+	}
+
+	/* Check for magic signature */
+	copy_from_user ( test, image->data, 0, sizeof ( test ) );
+	if ( ! ( ( ( memcmp ( test, ipxe_magic, sizeof ( test ) - 1 ) == 0 ) ||
+		   ( memcmp ( test, gpxe_magic, sizeof ( test ) - 1 ) == 0 )) &&
+		 isspace ( test[ sizeof ( test ) - 1 ] ) ) ) {
+		DBGC ( image, "Invalid magic signature\n" );
+		return -ENOEXEC;
+	}
+
+	return 0;
+}
+
+/** Script image type */
+struct image_type script_image_type __image_type ( PROBE_NORMAL ) = {
+	.name = "script",
+	.probe = script_probe,
+	.exec = script_exec,
+};
+
+/** "goto" options */
+struct goto_options {};
+
+/** "goto" option list */
+static struct option_descriptor goto_opts[] = {};
+
+/** "goto" command descriptor */
+static struct command_descriptor goto_cmd =
+	COMMAND_DESC ( struct goto_options, goto_opts, 1, 1, "<label>" );
+
+/**
+ * Current "goto" label
+ *
+ * Valid only during goto_exec().  Consider this part of a closure.
+ */
+static const char *goto_label;
+
+/**
+ * Check for presence of label
+ *
+ * @v image		Script
+ * @v offset		Offset within script
+ * @v label		Label
+ * @v command		Command
+ * @ret rc		Return status code
+ */
+static int goto_find_label ( struct image *image, size_t offset,
+			     const char *label, const char *command __unused ) {
+
+	/* Check label exists */
+	if ( ! label )
+		return -ENOENT;
+
+	/* Check label matches */
+	if ( strcmp ( goto_label, label ) != 0 )
+		return -ENOENT;
+
+	/* Update script offset */
+	script_offset = offset;
+	DBGC ( image, "[%04zx] Gone to :%s\n", offset, label );
+
+	return 0;
+}
+
+/**
+ * Terminate script processing when label is found
+ *
+ * @v rc		Line processing status
+ * @ret terminate	Terminate script processing
+ */
+static int terminate_on_label_found ( int rc ) {
+	return ( rc == 0 );
+}
+
+/**
+ * "goto" command
+ *
+ * @v argc		Argument count
+ * @v argv		Argument list
+ * @ret rc		Return status code
+ */
+static int goto_exec ( int argc, char **argv ) {
+	struct goto_options opts;
+	size_t saved_offset;
+	int rc;
+
+	/* Parse options */
+	if ( ( rc = parse_options ( argc, argv, &goto_cmd, &opts ) ) != 0 )
+		return rc;
+
+	/* Sanity check */
+	if ( ! current_image ) {
+		rc = -ENOTTY;
+		printf ( "Not in a script: %s\n", strerror ( rc ) );
+		return rc;
+	}
+
+	/* Parse label */
+	goto_label = argv[optind];
+
+	/* Find label */
+	saved_offset = script_offset;
+	if ( ( rc = process_script ( current_image, goto_find_label,
+				     terminate_on_label_found ) ) != 0 ) {
+		script_offset = saved_offset;
+		DBGC ( current_image, "[%04zx] No such label :%s\n",
+		       script_offset, goto_label );
+		return rc;
+	}
+
+	/* Terminate processing of current command */
+	shell_stop ( SHELL_STOP_COMMAND );
+
+	return 0;
+}
+
+/** "goto" command */
+struct command goto_command __command = {
+	.name = "goto",
+	.exec = goto_exec,
+};
+
+/** "prompt" options */
+struct prompt_options {
+	/** Key to wait for */
+	unsigned int key;
+	/** Timeout */
+	unsigned long timeout;
+};
+
+/** "prompt" option list */
+static struct option_descriptor prompt_opts[] = {
+	OPTION_DESC ( "key", 'k', required_argument,
+		      struct prompt_options, key, parse_key ),
+	OPTION_DESC ( "timeout", 't', required_argument,
+		      struct prompt_options, timeout, parse_timeout ),
+};
+
+/** "prompt" command descriptor */
+static struct command_descriptor prompt_cmd =
+	COMMAND_DESC ( struct prompt_options, prompt_opts, 0, MAX_ARGUMENTS,
+		       "[<text>]" );
+
+/**
+ * "prompt" command
+ *
+ * @v argc		Argument count
+ * @v argv		Argument list
+ * @ret rc		Return status code
+ */
+static int prompt_exec ( int argc, char **argv ) {
+	struct prompt_options opts;
+	char *text;
+	int rc;
+
+	/* Parse options */
+	if ( ( rc = parse_options ( argc, argv, &prompt_cmd, &opts ) ) != 0 )
+		goto err_parse;
+
+	/* Parse prompt text */
+	text = concat_args ( &argv[optind] );
+	if ( ! text ) {
+		rc = -ENOMEM;
+		goto err_concat;
+	}
+
+	/* Display prompt and wait for key */
+	if ( ( rc = prompt ( text, opts.timeout, opts.key ) ) != 0 )
+		goto err_prompt;
+
+	/* Free prompt text */
+	free ( text );
+
+	return 0;
+
+ err_prompt:
+	free ( text );
+ err_concat:
+ err_parse:
+	return rc;
+}
+
+/** "prompt" command */
+struct command prompt_command __command = {
+	.name = "prompt",
+	.exec = prompt_exec,
+};
diff --git a/roms/ipxe/src/image/segment.c b/roms/ipxe/src/image/segment.c
new file mode 100644
index 00000000..86fe4266
--- /dev/null
+++ b/roms/ipxe/src/image/segment.c
@@ -0,0 +1,91 @@
+/*
+ * Copyright (C) 2007 Michael Brown <mbrown@fensystems.co.uk>.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation; either version 2 of the
+ * License, or any later version.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
+ * 02110-1301, USA.
+ */
+
+FILE_LICENCE ( GPL2_OR_LATER );
+
+/**
+ * @file
+ *
+ * Executable image segments
+ *
+ */
+
+#include <errno.h>
+#include <ipxe/uaccess.h>
+#include <ipxe/io.h>
+#include <ipxe/errortab.h>
+#include <ipxe/segment.h>
+
+/**
+ * Segment-specific error messages
+ *
+ * This error happens sufficiently often to merit a user-friendly
+ * description.
+ */
+#define ERANGE_SEGMENT __einfo_error ( EINFO_ERANGE_SEGMENT )
+#define EINFO_ERANGE_SEGMENT \
+	__einfo_uniqify ( EINFO_ERANGE, 0x01, "Requested memory not available" )
+struct errortab segment_errors[] __errortab = {
+	__einfo_errortab ( EINFO_ERANGE_SEGMENT ),
+};
+
+/**
+ * Prepare segment for loading
+ *
+ * @v segment		Segment start
+ * @v filesz		Size of the "allocated bytes" portion of the segment
+ * @v memsz		Size of the segment
+ * @ret rc		Return status code
+ */
+int prep_segment ( userptr_t segment, size_t filesz, size_t memsz ) {
+	struct memory_map memmap;
+	physaddr_t start = user_to_phys ( segment, 0 );
+	physaddr_t mid = user_to_phys ( segment, filesz );
+	physaddr_t end = user_to_phys ( segment, memsz );
+	unsigned int i;
+
+	DBG ( "Preparing segment [%lx,%lx,%lx)\n", start, mid, end );
+
+	/* Sanity check */
+	if ( filesz > memsz ) {
+		DBG ( "Insane segment [%lx,%lx,%lx)\n", start, mid, end );
+		return -EINVAL;
+	}
+
+	/* Get a fresh memory map.  This allows us to automatically
+	 * avoid treading on any regions that Etherboot is currently
+	 * editing out of the memory map.
+	 */
+	get_memmap ( &memmap );
+
+	/* Look for a suitable memory region */
+	for ( i = 0 ; i < memmap.count ; i++ ) {
+		if ( ( start >= memmap.regions[i].start ) &&
+		     ( end <= memmap.regions[i].end ) ) {
+			/* Found valid region: zero bss and return */
+			memset_user ( segment, filesz, 0, ( memsz - filesz ) );
+			return 0;
+		}
+	}
+
+	/* No suitable memory region found */
+	DBG ( "Segment [%lx,%lx,%lx) does not fit into available memory\n",
+	      start, mid, end );
+	return -ERANGE_SEGMENT;
+}